A number of potential functions used in the literature fit this definition, including the exponential potential function \(\phi (z) = e^{-z}\)  used by AdaBoost [1]}, the mixed linear/exponential potential function \(\phi (z)\)  which is \(1-z\)  if \(z\le 0\)  and is \(e^{-z}\)  if \(z>0\)  used by MadaBoost [2]}, and the logistic function \(\phi (z) = \ln (1+e^{-2z})\)  used by LogitBoost [3]}.
